Organ pedal tone generator

ABSTRACT

Tone generator system including an oscillator comprising a capacitor and unijunction transistor, with pedals applying potentials representing different notes to a constant current source for controlling the same to charge the oscillator capacitor at different rates for producing the frequencies of different notes. A second control of frequency is provided by changing the potential applied to the gate of the unijunction transistor. The gate potential can be reduced to change the oscillator from the frequency of the root note of a chord to that of the 5th note of the chord, for playing a bass rhythm. The oscillator frequency may be in the frequency range of 8 foot tones, and the sawtooth wave may be directly keyed for providing string bass sounds. A frequency divider triggered by the oscillator produces a square wave at one half the frequency, which is summed with the sawtooth wave to provide a sawtooth wave at one half the frequency, or in the 16 foot tone octave. This may be keyed and filtered for providing a 16 foot diapason tone. The square wave may also be keyed and filtered to provide a 16 foot bourdon tone.

United States Patent 1191 Southard [451 Sept. 24, 1974 [75] Inventor:James S. Southard, Elkhart, Ind. i gsxgj Assigneei Conn, -3 Elkhart,Attorney, Agent, or Firm-Mueller, Aichele & Ptak [22] Filed: Apr. 30,1973 21 Appl. No.: 355,780 [57] ABS TRAC T Tone generator system mcludmgan osclllator comprising a capacitor and unijunction transistor, with[52] US. Cl 84/ 1.01, 84/ 1.03, 84/1.24, pedals applying potentialsrepresenting different mes 84/DIG- to a constant current source forcontrolling the same Cl. t h g th ill t p it t diff t rates f [58] heldof Search 84/101 11171 122-1124 producing the frequencies of differentnotes. A second 84/DIG- 1316- 12 control of frequency is provided bychanging the potential applied to the gate of the unijunctiontransistor. 1 References cued The gate potential can be reduced tochange the oscil- UNITED STATES PATENTS lator from the frequency of theroot note of a chord to 3,443,463 5/1969 Campbell 84/1.01 that of the5th no of the o for p y ng a ss 3,538,804 11/1970 George 84/1.0l rhythm.The osc1llator frequency may be in the fre- 3,603,309 1971 ya 2 X quencyrange of 8 foot tones, and the sawtooth wave 3,609,201 9/1971 Adachl,84/ 1.01 may p directly keyed for providing string bass 1 Kmepkamp soundA frequency oscillator $23732? {2131} EEK/ 31/1832x95112929,saaarsflasat,9991192199.?599999i 481 12/1971 Bunger' 84/l'03which is summed with the sawtooth wave to provide a 316651089 5/1972stearns ififiz III: 84/l:01 11/1999 Wave at half the 315E219! iH. h..1.3,706,837 12/1972 Arsem et al. s4/1.03 foot 19 octave- T111? y be keyedand filtered for 3,707,594 12/1972 lchikawa s4/1.03 provldmg a 16 footdlapason tone. The square wave 3,708,602 1/1973 Hiyama 84/1.03 may alsobe keyed and filtered to provide a 16 foot 3,740,449 6/1973 Southard i84/1.0l bourdon tone. 3,743,757 7/1973 Okamoto.... 84/l.03 3,764,72210/1973 Southard 84/1.03 l6 Clalms, 4 ng gures l2\- 4 |t 5 IB l 2O l 22I 24) R mule CONSTANT OSCILLATOR SAMPLE KEYER Z' Q Z CIRCUIT cmcun2332i? 8 FT I BASS a R PEDAL ALTERNATE KEYER DIAPASON KEYBOARD FIFTH 2645 1 2a ,3o 4 3222 I FILTE AUTOMATIC DIVIDER KEYER BOURBON RHYTHM FT 16'ORGAN PEDAL TONE GENERATOR minim-strewn ml 2 N 2 mom Om O 2 IkrIm mmh zu@ZEPW mmkJE ORGAN PEDAL TONE GENERATOR BACKGROUND OF THE INVENTION Thereis a large demand for inexpensive electric organs which have a oneoctave,'or 13 note, pedal board for controlling an independent tonegenerating system. One such system is described in Pat. No. 3,180,9l8,issued Apr. 27, 1965, to Donald K. Harmon, and assigned to C .G. ConnLimited, the assignee of the present application. Although such tonegenerators provide only one bass frequency at a time, frequency dividersmay be used to simultaneously provide a tone in a lower octave. It isdesired to provide tones having different characteristics such as astring bass, a diapason, and a bourdon or flute tone.

In view of the common use of rhythm systems with organs, it is alsodesired to provide a pedal tone generatorwhich is adaptable to be usedin cooperation with a rhythm system. It is desired that the pedalgenerator 1 be suitable for use in connection with chords, wherein theroot tone and'the th tone of the chord are played alternately. Also itis desired that the pedal generator system be adapted to be keyed inaccordance with rhythm patterns.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide an improved tone generator system adapted to provide the such anoscillator which produces a sawtooth wave form, and which triggers adivider to produce a square v wave at one half the frequency, with thesawtooth wave and the square wave being combined to provide various waveforms which are keyed and filtered to provide desired pedal tones.

Another object of the invention is to provide a pedal generator systemincluding an oscillator and keyers which are adapted to be controlled bya rhythm system for providing various rhythm effects.

Still another object of the invention is to provide a keyer circuit foruse witha rhythm system which prevents double triggering by actuation ofthe pedal slightly out of tempo with the rhythm beat.

In practicing the invention, a pedal tone generating system is providedwherein the pedals select different potentials from a voltage divider,with the selected potentials controlling a constant current source tocharge a capacitor at a fixed rate. A unijunction transistor is coupledto the capacitor to discharge the same, forming an oscillator whichprovides a sawtooth wave. Waves corresponding to the notes in an octavecan be provided by changing the current supplied by the con- ,stantcurrent source, to provide the notes in the 8 foot octave. In additionto control of the frequency of the wave by the current source, thepotential applied to the gate of the unijunction transistor can bechanged to change the duration of each ramp to thereby control theperiod and frequency of the produced wave. The change in the gatepotential can be controlled by a rhythm system to automatically changethe gate potential to change the frequency from the root note of a chordto the 5th note thereof, with the frequency automatically alternatingbetween the root and the 5th tones as desired for a rhythm sound. Theoscillator triggers a frequency divider for producing a square wave atone half the frequency of the sawtooth wave, to provide tones in the 16foot octave. The square wave and the sawtooth wave may be summed toprovide a third output, which is a sawtooth wave in the 16 foot octave.The three different outputs may be individually keyed and filtered toprovide different pedal tone sounds. The keyers may also be controlledby the rhythm system, to provide desired rhythm effects. The keyercontrol circuit prevents double triggering of the keyers by operation ofa pedal slightly out of tempo with the rhythm beat.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing thepedal generator system of the invention;

FIG. 2 is a chart showing waveforms developed in the system of FIG. 1;

FIG. 3 is a circuit diagram of the tone generator system of FIG. 1; and

FIG. 4 is a chart illustrating the operation of the keyer controlcircuit.

DETAILED DESCRIPTION In FIG. lthe organ pedal tone generation system ofthe invention is shown in block diagram form. A keyboard 10 controls atuning network 12 which produces potentials in accordance with theparticular notes selected. The keyboard may be a pedal board which isused with an organ having one or more other keyboards or manuals. Thepotential from the tuning network is applied to a memory circuit 14,which controls a cur rent source 16, which in turn controls thefrequency of an oscillator 18. The oscillator 18 produces tones in the 8foot octave of the organ. The tones from the oscillator 18 are sampledby the circuit 20 and applied to a keyer 22 for producing string basstones. The tones from keyer 22 are applied through the format filter 24to the audio system 26.

The output of the oscillator 18 is also applied to a divider 28 whichproduces tones in the 16 foot octave. The tones from the divider 28 areapplied to keyer 30 which keys the 16 foot tones. The 16 foot tones areapplied through filter 32 which may modify the shape of the wave toproduce the bourdon sounds, and then to the audio system 26.

The 8 foot tones from the circuit 20 are applied to one end ofpotentiometer 35, and 16 foot tones from the divider 28 are applied tothe other end thereof. The 8 and I6 foot tones are. summed and derivedfrom the intermediate terminal 36 of the potentiometer and applied tokeyer 38. The output of keyer 38 is applied through diapason filter 40to the audio system 26.

In addition to the operations controlled by the keyboard 10, anautomatic rhythm system may be provided which produces various beatpulses for different rhythm patterns determined by controls on therhythm system 45. Outputs from the keyboard 10 and from the rhythmsystem 45 are applied to an alternate 5th circuit the frequency of theoscillator 18 to produce a different note, as will be fully described.Pulses from the keyboard 10 and from the rhythm system 45 are alsoapplied to the keyers 22, 30, and 38 to control the same.

In FIG. 2 there is shown the waveforms utilized in the pedal generatorsystem. Line A shows the waveform produced by the oscillator 18, andwhich is derived therefrom and applied to the sample circuit 20. This isa sawtooth waveform having a frequency in the 8 foot octave. Aspreviously stated, the frequency is controlled by the tuning circuit 12in response to operation to the keyboard 10 (FIG. 1). The frequency ofthe oscillator may also be controlled by the alternate 5th circuit 48,as will be described. Line B shows a second output which is derived fromthe oscillator 18 which is a pulse output produced at the time thesawtooth wave drops. The pulse output B is applied to the divider 28 tocause the divider to produce the square wave output as shown in line C.As previously stated, this is at one half the frequency of the sawtoothwave in line A, and has a frequency in the l6 foot octave. The signalproduced at point 36 of the potentiometer 35 is shown in line D of FIG.2. This is a sawtooth wave having the same frequency as the wave shownin line C. This is formed by the addition of the waves shown in line Aand C. Accordingly, the circuit provides sawtooth waves at frequenciesin the 8 and 16 foot octaves, and a square wave in the 16 foot octave.The waves after keying are shaped by filters to provide the desiredmusical wave shapes.

In FIG. 3 there is shown a circuit diagram of the pedal generatingsystem which follows the block diagram of FIG. 1. The keyboard 10includes two switches 50 and 52 which are operated by each key or pedal.In the system of FIG. 3, l3 switches 50 and 52 are provided for a 13note pedal board, which provides the notes inan octave from C1 to B1,and including the note C2 of the next higher octave. The notes producedare indicated adjacent the switches.

The switches 50 provide a different potential for each note in thekeyboard which is related to the frequency 'of the note. Four voltagedivider strings 54, 55, 56 and 57 are provided from a regulatedpotential applied by conductor 60, which is connected through resistor61 to the four voltage divider strings. The regulated potential onconductor 60, which is shown in FIG. 3 as +18 volts, is provided byregulator 62 which is energized from the +30 volts supply. Each dividerstring has a plurality of series connected resistors with taps thereonto produce different voltages. The switches 50, when operated, are eachconnected to a tap on one of the voltage divider strings, and derivesthe potential therefrom which is applied to conductor.65. Each of theswitches 50 is a double throw switch, and an operated I switch appliesthe potential through the normally closed contacts of the switches ofthe pedal board associated with the notes of lower frequency. Thearrangement shown is known in the art, being shown in Pat. No.3,180,918, referred to above. In the circuit shown in FIG. 3, in theevent that two switches 50 are operated, only the potential provided bythe switch associcharge the same. This potential is applied throughresis- 'tor 67 to the gate electrode of field effect transistor 80.

The drain electrode of transistor is coupled to conductor 60 providingthe regulated potential, and the source electrode is connected throughpotentiometer 81 and resistor 82 to ground.

Current source transistor 84 has its base electrode connected to thevoltage divider formed by resistors 82 and 83, and its emitter electrodeconnected through resistor 85 to the intermediate point on potentiometer81. The collector electrode of transistor 84 is connected to capacitor86 and provides a constant current supply to charge this capacitor at arate which depend upon the bias voltage applied to the gate electrode ofthe field effect transistor 80.

Connected across capacitor 86 is a unijunction transistor 88 having itsbase electrode connected through resistor 89 to ground, and its emitterelectrode connected to the high potential side of capacitor 86. The gateelectrode of unijunction transistor 88 is connected to a voltage dividerincluding resistors 90 and 91 connected between the regulated potentialline 60 and ground. The potential on line 60 is held within close limitsby the regulator 62 which can be of known construction. When thecapacitor 86 charges to a voltage such that the emitter of transistor 88rises to the gate voltage, the transistor 88 will conduct to dischargecapacitor 86 through resistor 89. The time required for the capacitor tocharge will depend upon the charging rate, which is controlled by thefield effect transistor 80. Accordingly, the potential applied by thekey switches will control the charging rate and the time interval beforefirings, to thereby control the period and frequency of the waveproduced across capacitor 86 by the charge and discharge thereof.

A field effect transistor 94 has its gate connected to the highpotential side of capacitor 86, its drain connected to the regulatedpotential on conductor 60, and its source connected through resistor 95to ground. This transistor forms a source follower to provide apotential on conductor 96 which corresponds to the voltage acrosscapacitor 86. The source follower circuit, including transistor 94 andresistor 95, forms the sample circuit 20 shown in FIG. 1. Accordingly, atriangular wave is developed on conductor 96, which is the waveformshown on line A of FIG. 2.

The frequency divider 28 shown in FIG. 1, is provided in the circuit ofFIG. 3 by the multivibrator including transistors 100 and 102. The twotransistors are connected in a bistable multivibrator circuit, withtheir emitter electrodes connected together and to resistor 89, throughwhich capacitor 86 is discharged. As is well known, the transistors 100and 102 will be alternately conducting as the'bistable multivibratorchanges states. The discharge of capacitor 86 through resistor 89 willproduce a positive going pulse thereacross which is directly applied tothe emitter electrodes of transistors I00 and 102. These pulses areshown by line B of FIG. 2, and will act to turn off whichever transistor100 or 102 is conducting, causing its collector potential to rise. Thispotential is applied to the base of the other transistor turning it on.Inasmuch as the positive going pulse is produced across resistor 89 onceduring each cycle of the waveform produced across capacitor 86, themultivibrator will change state once during each cycle with the resultthat a complete cycle is produced by the multivibrator during each 2cycles of the wave across capacitor 86. A square wave is produced at thecollector of each transistor 100 and 102, as shown in line C of FIG. 2,with the square wave being derived in the circuit of FIG. 3 from thecollector of transistor 100.

The sawtooth wave on conductor 96 and the square wave on conductor 103connected to collector of transistor 100, are applied to the summingnetwork 35, which includes resistors 104, 105 and 106. The summed outputis derived by conductor 108 connected to the junction 36 betweenresistors 105 and 106. The

plication Ser. No. 156,326, filed June 24, 1971, and

now U.S. Pat. 3,740,449.

The alternate 5th circuit is connected to the gate of transistor 88, andincludes resistors 109 and 110, diode 111, and resistor 112 connected tothe regulated conductor 60. Transistor 114 has its collector connectedto the junction between diode 111 and resistor 112, and its emitterconnected to ground. A potential is applied from terminal 115 of therhythm system 45 through resistor 116 to the base electrode oftransistor 114 to selectively render the same conducting. This willbring the collector of transistor 114 near ground, so that the junctionbetween diode 111 and resistor 112 will be brought near groundpotential. This will effectively connect the resistors 109 and 110, anddiode 111 in parallel with resistor 91 to reduce the gate potentialapplied to unijunction transistor 88. This reduced gate potential willcause the unijunction transistor 88 to fire when capacitor 86 charges toa lower value, to shorten the period of the wave and increase thefrequency produced when transistor 114 conducts.

In the event that the switch 50 of an actuated pedal provides apotential to cause the oscillator 18 to operate to produce the note C,the action of the alternate 5th circuit will cause the oscillatorfrequency to increase to produce the note G. The note G is the 5th notein the chord in which the note C is the root. Accordingly, operation oftransistor 114 causes the oscillator to change from the root note C tothe 5th note G.

-An external terminal 92 is connected to the gate electrode ofunijunction transistor 88, to which potentials can be applied to controlthe frequency of oscillation, as may be desired. By applying differentpotentials to terminal 92, the frequency produced by the oscillatorformed by capacitor 86 and transistor 88 can. be changed in steps, toprovide a walking bass effect, for example.

The keyer 38 for the 16 foot diapason tone includes transistor 120. Thesawtooth wave output from point 36 is applied through resistor 121 tothe emitter of trandiapason tone. The charge of capacitor 122 iscontrolled by transistor 125 which forms a two input gate. The base oftransistor 125 is connected by resistor 126 to conductor 129 which isconnected to terminal 127 of the rhythm system 45. Conductor 129 is alsoconnected to the collector of transistor 131, which is controlled by thesignal applied from terminal 130 of the rhythm system. The emitter oftransistor 125 is connected to conductor 132 which is connected to thepedal switches 52, so that when any pedal -*(or key) switch is operated,the regulated potential on line 60 is applied to the emitter oftransistor 125.

When the rhythm system is not being used, a ground is applied toterminal 127 and through resistor 126 to ground the base of transmitter125 so that it is rendered conductive. Then when a pedal switch 52 isoperated, the potential applied on line 132, which may be plus 18 volts,is coupled from the emitter to the collector of transistor 125 and actsto charge capacitor 122. The collector of transistor 125 is connected tocapacitor 122 by diode 134 and resistor 135, which supply current tocharge the capacitor. The potential developed across capacitor 122 isapplied through resistor 123 to the base of transistor 120 to render thesame conducting, so that the diapason tone applied to the emitterthereof is coupled to the collector and applied through capacitor 138 tothe base of transistor 140. The rate of charge of capacitor 122 controlsthe attack of the diapason tone. Transistor 140 amplifies the diapasonsignal andapplies the same to the diapason filter 40, from which it isapplied to audio system 26.

The decay of the diapason tone is controlled by the discharge rate ofcapacitor 122. When the pedal switch 52 is released or opened, capacitor122 normally discharges through resistors 123 and 142, and diodeconnected transistor 143. This discharge rate may be relatively slow toprovide a sustain effect. If it is desired to provide a rapid decay ofthe tone, a negative potential can be applied to capacitor 122 fromterminal 145,

through operation of a tab switch of the organ. This potential iscoupled through resistor 146 to the capacitor 122, and the negativepotential will cause the capacitor 122 to discharge rapidly to reducethe sustain time.

The keyer 22 for the 8 foot tone is similarly controlled by a two inputgate formed by transistor 150. This transistor also has its emitterconnected to conductor 132, which is connected to the pedal switches 52to apply the potential on regulated conductor 60 thereto. The baseelectrode of transistor 150 is connected by resistor 151 and conductor129 to terminal 127 of the rhythm system 45, and is also coupled to thecollector of transistor 131, the base of which is connected to terminal130 of the rhythm system. The keyer 22 includes transistor 154, havingits emitter connected to conductor 96 through capacitor 156 to apply the8 foot tone thereto. This tone is gated by transistor 154 which controlsthe attack and decay characteristics of the tone.

When the rhythm system is off and the base of transistor 150 isgrounded, actuation of a pedal switch 52 will apply the regulatedpotential from the emitter to the collector of transistor 150, andacross resistors 158, 159 and 160. The voltage across resistor 160 iscoupled through capacitor 162 and across resistor 163 to the base oftransistor 165. The potential applied through transistor 150 causestransistor 165 to initially be highly conductive which, in turn, renderstransistor 166 conducting. This action results from the current flow tor154 to be conducted to the collector thereof, and i applied throughcoupling capacitor 175 to the base of transistor 176. The voltagedivider circuit formed by variable resistor 185 and resistors 186, 187and 188, applies a potential through resistor 189 to the base oftransistor 154 to control the threshold voltage required acrosscapacitor 170 to render transistor 154 conducting. Resistor 188 may be atemperature responsive resistor to compensate the threshold for changesin temperature. The turn on of transistor 154 controls the attack of the8 foot tone to provide a string bass effect.

Transistor 176 amplifies the string bass signal and applies the same tothe'string filter 24 which, in turn, applies the'signal to the audiosystem 26.

When the pedal switch 52 is released, the charging potential is removedfrom capacitor 170 and this capacitor discharges through resistor 180and diode 182, which are connected to terminal 184. The potential atterminal 184 can be controlled between two values by a tab switch of theorgan which is connected thereto. Capacitor 170 will initially dischargerapidly to the potential applied at terminal 184, and then continue todischarge at a slower rate through resistors 172 and 173, and thebase-emitter junction of transistor 154. By controlling the potentialapplied at terminal 184,-the point at which the rapid dischargeterminates can be controlled, to thereby control the decaycharacteristics of the string bass tone.

A further discharge path is provided for capacitor 170 through thecollector-base junction of transistor 166, resistors 167 and 168, diode190 and resistor 191 connected to terminal 192. Terminal 192 isselectively connected to ground by an organ tab switch. When terminal192 is grounded, capacitor 170 will discharge very rapidly so that therewill be substantially no sustain action, and the string bass tone willterminate abruptly. The action of the circuit to charge and dischargecapacitor 170 is described and claimed in my Pat. No. 3,617,605 issuedNov. 2, 1971. Resistor 173 is provided in parallel with resistor 172 inthe circuit to provide the desired discharge characteristics. This isrequired since the part of the circuit enclosed by dotted lines may beprovided as an integrated circuit for general application. The externalresistor 173 modifies the decay characteristics of the keyer andprovides the desired characteristics for a particular application.

When the rhythm system 145 is operative, the ground will be removed fromterminal 127 and applied to terminal 128, and automatic rhythm beatpulses will be applied to terminal 130. These pulses are applied acrossresistors 194 and 195 and through capacitor 196 to the base oftransistor 131. This will cause transistor 131 to conduct on each beatto effectively ground conductor 129 to render the gate transistor 125 inthe dia pason keyer circuit, and the gate transistor 150 in the stringbass keyer circuit conducting. Accordingly, when a pedal is operated toclose a switch 52, the keying potential will be intermittently appliedthrough the transistors and in response to the beat pulses from therhythm system.

Keyer 125 will operate when a pedal is first operated to close a switch52 without receiving ground from transistor 131 in response to a rhythmpulse. This results from the ground at terminal 128 being appliedthrough diode 198, capacitor 199 and resistors 206 and 126- to the baseof transistor 125. The operated switch 52 applies positive potentialthrough resistor 207 to charge capacitor 199 to turn off the keyer 125after a short time. The keyer 125 will therefore operate only once fromactuation of a pedal, but will be operated in response to rhythm beatpulses by action of transistor 131 to ground conductor 132, whichgrounds the base of transistor 125.. Keyer 150 for the string bass toneis not keyed in this way, as there is no capacitor connected to the baseof transistor 150.

Terminal 200 is connected to conductor 132 so that the potential appliedby actuation of a pedal switch 52 can be applied to an externalauxiliary device connected to the organ, or an external potential can beapplied at this point to operate the keyers. Similarly, terminal 202 isconnected to the collector of transistor 150, so that the potentialapplied therefrom which controls the string bass keyer can be applied toan external auxiliary device, or an external potential can be applied tooperate the keyer.

A large capacitor 205 can be connected from terminal 200 to terminal 203which is connected to the emitter of transistor 131, to prevent doubletriggering of transistor 131. FIG. 4 shows the action of this circuitwhen the pedal is operated at a time slightly after a rhythm pulse isapplied, with the rhythm pulses being shown by line E and the operationof the pedal and switch 52 by line F. When the first rhythm pulse E, isreceived, the transistor 131 will be rendered conducting. Then when apedal is operated and a switch 52 is closed, the regulated potential isapplied through the switch to conductor 132 and to terminal 200. Thispotential will be applied through capacitor 205 to the emitter oftransistor 131, so that transistor 131 will not conduct in response tothe next rhythm pulse E as the emitter potential is above the potentialof the pulse applied to its base. The potential applied to the emitterof transistor 131 will decrease exponentially as capacitor 205 charges,as shown by curve G which is superimposed on the pulses E. Transistor131 will conduct in response to the next rhythm pulse 13;, as theemitter potential has fallen below the potentialof the rhythm pulsesfrom terminal 130. Transistor 131 is, therefore, rendered conductiveto'apply a ground to conductor 129 and cause transistor gates 150 and125 to conduct and turn on the diapason and string bass keyers.

The action of capacitor 205 creates a time when rhythmpulses cannot firethe keyers just after switch 52 closes, eliminating a double triggeringwhen the pedal is played slightly out of tempo, which is objectionablemusically. Other circuit arrangements can be provided to prevent suchdouble triggering.

The tone generator circuit which has been described has been found to behighly effective to provide pedal tones for an electric organ. Thecircuit can be used with a rhythm system so that the pedal tones areprovided capacitor means for developing a voltage wave, current supplymeans connected to said capacitor means for supplying current thereto tocharge said capacitor means so that the voltage thereacross riseslinearly,

switch means connected to said capacitor means for discharging saidcapacitor means, said switch means having a control element forreceiving a control potential which causes said switch means to conductand discharge said capacitor means in response to a voltage across saidcapacitor means which reaches said control potential,

circuit means connected to said control element of said switch means forapplying a first potential to said control element which causes saidswitch means to conduct to discharge said capacitor means to produce awave thereacross which has the frequency of a first musical note, and

control means connected to said circuit means for causing said circuitmeans to establish a second potential which causes said switch means toconduct to discharge said capacitor means to produce a wave thereacrosswhich has a frequency different from said frequency of the first musicalnote.

2. A tone generator circuit in accordance with claim 1 further includingtuning means connected to said current supply means for causing saidcurrent supply means to supply currents of different values to chargesaid capacitor means at different rates, with the values of the currentssupplied being related tosaid first potential applied to said switchmeans by said circuit means so that the waves across said'capacitormeans have the frequencies of different musical notes.

' 3. A tone generator circuit in accordance with claim one half thefrequency of the wave developed across said capacitor means, andcombining means coupled to said capacitor means and to said frequencydivider means to provide a resultant wave.

5. The circuit of claim 4 further including a first keying means coupledto said combining means for keying the resultant wave produced thereby,and second keying means coupled to said capacitor means for keying thewave developed thereacross.

6. The circuit of claim 5 further including first and second gate meansfor controlling said first and second keying means, with each of saidgate means having a first input coupled to a keyboard and a second inputcoupled to rhythm means.

7. The circuit of claim 1 wherein said switch means is formed by aunijunction transistor having a gate electrode, and said gate electrodeforms said control element of said switch means.

bination,

oscillator means for producing waves corresponding to musical notesincluding capacitor means across which the waves are developed, meansconnected to said capacitor means for applying current thereto to chargesaid capacitor means, and switch means connected to said capacitor meansfor discharging the same in response to a voltage across said capacitormeans which reaches a predetermined potential,

a control circuit connected to said switch means and applying a controlpotential to said switch means for actuating the same, said controlcircuit including first means for establishing a first control potentialwhich causes said switch means to conduct to discharge said capacitormeans to produce a wave thereacross which has the frequency of a firstmusical note, and second means coupled to said first means and causingsaid first means to establish a second potential which causes saidswitch means to conduct to discharge said capacitor means to produce awave thereacross of a higher frequency of a second musical note, I

gating means coupled to said capacitor means for selectively passing thewaves developed thereacross and controlling the attack and decay of themusical notes produced by said waves, and

rhythm means coupled to said second means of said control circuit and tosaid gating means for controlling said second means and said gatingmeans in accordance with a rhythm pattern.

9. An organ system in accordance with claim 8 wherein said, gating meansincludes means for changing the decay of the waves passed thereby.

10. An organ system in accordance with claim 8 further including akeyboard coupled to said gating means for controlling the same.

11. An organ system in accordance with claim 10 including means coupledto said keyboard and to said means for applying current to saidcapacitor means for controlling such current in accordance with theoperation of said keyboard.

12. An organ system in accordance with claim 10 further includingcircuit means coupling said rhythm means and said keyboard to saidgating means for producing a gating potential and applying suchpotential to said gating means in response to a pulse from said rhythmmeans and operation of said keyboard, and means coupled to said circuitmeans for disabling said circuit means for a predetermined time afterthe gating potential is produced.

13. An organ tone generator system including in combination;

oscillator means for producing waves corresponding to musical notes,

gating means coupled to said oscillator means and responsive to a gatingpotential for selectively passing the waves from said oscillator means,

a control circuit for said gating means for applying a gating potentialto said gating means,

keyboard means coupled to said control circuit for selectively applyinga potential thereto, rhythm means coupled to said control circuit forapplying thereto pulses corresponding to the beats of a rhythm,

said control circuit being responsive to the potential from saidkeyboard and the pulses from said rhythm means to produce a gatingpotential to operate said gating means to pass the wave from saidoscillator means, and

disabling means coupled to said control circuit and operative inresponse to the gating potential to disable said control circuit andprevent the application of the gating potential to said gating means fora predetermined time period.

14. The organ tone generator system of claim 13 wherein said controlmeans has an input for receiving pulses from said rhythm means and anoutput for applying the gating potential to said gating means, andincluding disabling means coupled from said output to said input fordisabling said control means for a predetermined period. v

15. The organ tone generator system of claim l4 wherein said disablingmeans coupled from said output to said input is a capacitor whichapplies a disabling potential to said input which decrease exponentiallyto a value such that said input respond to said pulses applied thereto.

16. The organ tone generator system of claim 13 wherein said gatingmeans includes first and second gates and said control means includesfirst and second circuit portions coupled to said first and secondgates, respectively, with said first circuit portion causing operationof said first gate in response to the potential from said keyboard andcausing further operation of said first gate in response to pulses fromsaid rhythm means.

1. A tone generator circuit including in combination, capacitor meansfor developing a voltage wave, current supply means connected to saidcapacitor means for supplying current thereto to charge said capacitormeans so that the voltage thereacross rises linearly, switch meansconnected to said capacitor means for discharging said capacitor means,said switch means having a control element for receiving a controlpotential which causes said switch means to conduct and discharge saidcapacitor means in response to a voltage across said capacitor meanswhich reaches said control potential, circuit means connected to saidcontrol element of said switch means for applying a first potential tosaid control element which causes said switch means to conduct todischarge said capacitor means to produce a wave thereacross which hasthe frequency of a first musical note, and control means connected tosaid circuit means for causing said circuit means to establish a secondpotential which causes said switch means to conduct to discharge saidcapacitor means to produce a wave thereacross which has a frequencydifferent from said frequency of the first musical note.
 2. A tonegenerator circuit in accordance with claim 1 further including tuningmeans connected to said current supply means for causing said currentsupply means to supply currents of different values to charge saidcapacitor means at different rates, with the values of the currentssupplied being related to said first potential applied to said switchmeans by said circuit means so that the waves across said capacitormeans have the frequencies of different musical notes.
 3. A tonegenerator circuit in accordance with claim 1 wherein said secondpotential produced by said circuit means is related to said firstpotential to produce a second musical note which is related to saidfirst musical note as the fifth and root notes in a chord.
 4. A tonegenerator circuit in accordance with claim 1 further including frequencydivider means coupled to said switch means for producing a rectangularwave at one half the frequency of the wave developed across saidcapacitor means, and combining means coupled to said capacitor means andto said frequency divider means to provide a resultant wave.
 5. Thecircuit of claim 4 further including a first keying means coupled tosaid combining means for keying the resultant wave produced thereby, andsecond keying means coupled to said capacitor means for keying the wavedeveloped thereacross.
 6. The circuit of claim 5 further including firstand second gate means for controlling said first and second keyingmeans, with each of said gate means having a first input coupled to akeyboard and a second input coupled to rhythm means.
 7. The circuit ofclaim 1 wherein said switch means is formed by a unijunction transistorhaving a gate electrode, and said gate electrode forms said controlelement of said switch means.
 8. An organ tone generator systemincluding in combination, oscillator means for producing wavescorresponding to musical notes including capacitor means across whichthe waves are developed, means connected to said capacitor means forapplying current thereto to charge said capacitor means, and switchmeans connected to said capacitor means for discharging the same inresponse to a voltage across said capacitor means which reaches apredetermined potential, a control circuit connected to said switchmeans and applying a control potential to said switch means foractuating the same, said control circuit including first means forestablishing a first control potential which causes said switch means toconduct to discharge said capacitor means to produce a wave thereacrosswhich has the frequency of a first musical note, and second meanscoupled to said first means and causing said first means to establish asecond potential which causes said switch means to conduct to dischargesaid capacitor means to produce a wave thereacross of a higher frequencyof a second musical note, gating means coupled to said capacitor meansfor selectively passing the waves developed thereacross and controllingthe attack and decay of the musical notes produced by said waves, andrhythm means coupled to said second means of said control circuit and tosaid gating means for controlling said second means and said gatingmeans in accordance with a rhythm pattern.
 9. An organ system inaccordance with claim 8 wherein said gating means includes means forchanging the decay of the waves passed thereby.
 10. An organ system inaccordance with claim 8 further including a keyboard coupled to saidgating means for controlling the same.
 11. An organ system in accordancewith claim 10 including means coupled to said keyboard and to said meansfor applying current to said capacitor means for controlling suchcurrent in accordance with the operation of said keyboard.
 12. An organsystem in accordance with claim 10 further including circuit meanscoupling said rhythm means and said keyboard to said gating means forproducing a gating potential and applying such potential to said gatingmeans in response to a pulse from said rhythm means and operation ofsaid keyboard, and means coupled to said circuit means for disablingsaid circuit means for a predetermined time after the gating potentialis produced.
 13. An organ tone generator system including incombination; oscillator means for producing waves corresponding tomusical notes, gating means coupled to said oscillator means andresponsive to a gating potential for selectively passing the waves fromsaid oscillator means, a control circuit for said gating means forapplying a gating potential to said gating means, keyboard means coupledto said Control circuit for selectively applying a potential thereto,rhythm means coupled to said control circuit for applying thereto pulsescorresponding to the beats of a rhythm, said control circuit beingresponsive to the potential from said keyboard and the pulses from saidrhythm means to produce a gating potential to operate said gating meansto pass the wave from said oscillator means, and disabling means coupledto said control circuit and operative in response to the gatingpotential to disable said control circuit and prevent the application ofthe gating potential to said gating means for a predetermined timeperiod.
 14. The organ tone generator system of claim 13 wherein saidcontrol means has an input for receiving pulses from said rhythm meansand an output for applying the gating potential to said gating means,and including disabling means coupled from said output to said input fordisabling said control means for a predetermined period.
 15. The organtone generator system of claim 14 wherein said disabling means coupledfrom said output to said input is a capacitor which applies a disablingpotential to said input which decrease exponentially to a value suchthat said input respond to said pulses applied thereto.
 16. The organtone generator system of claim 13 wherein said gating means includesfirst and second gates and said control means includes first and secondcircuit portions coupled to said first and second gates, respectively,with said first circuit portion causing operation of said first gate inresponse to the potential from said keyboard and causing furtheroperation of said first gate in response to pulses from said rhythmmeans.